Contaminant of the Month: Non-Compostable Green Bags

Film plastic is, undeniably, one of the most prevalent contaminants migrating its way into industrial compost facilities. When analyzing the source of non-compostable films, one simply needs to follow the food scraps to see how established systems of sourcing and sorting has been hindered by the onslaught of non-compostable green bags coming into the market.

The use of compostable bags has been instituted in many cities providing food scrap collection programs, helping to minimize the “yuck” factor for citizens and businesses working to source separate food scraps from the garbage. Thankfully, compostable bag manufacturers in the U.S. have worked to make their products a translucent light green, which makes them visually distinctive from white plastic grocery bags, or clear produce bags. These distinguishing colors are also helpful for compost facility operators. On an hourly basis, several tons of compostable materials are offloaded by truck at these facilities, and compostable green bags, historically, have been easily identifiable from 10 feet away (called the “10-foot rule”) by the folk’s high off the ground in heavy equipment working to move, grind and process food scraps and yard clippings.

Unfortunately, a growing number of green non-compostable bags associated with food scraps are provided in stores (like organic produce bags or take out deli bags), which confuses the consumer into thinking they must be compostable, thwarting the facility operators’ efforts to distinguish appropriate feedstocks for processing. Thus, the bags can’t be distinguished and remain in the active composting process, while coming out the end of the composting cycle. From there, they must be blown out, suctioned, or mechanically removed through large twirling screening equipment. This is costly for the compost facility, while leading to the loss of good organic material, a portion of which ends up getting removed with the plastics and shipped to the landfill.

To address this issue, on July 1, 2017, the City of Seattle updated their bag ban ordinance to require that only compostable bags used in grocery retail can be tinted green or brown, while non-compostable bags are prohibited from using these colors. See summary here.

This will help curtail the “look-alike” issues between compostable and non-compostable films, and hopefully help correct this systems problem in sorting the appropriate bags.

CMA’s hope is that more associations, states and cities will adopt these types of forward thinking policies, and helping to make compost feedstocks cleaner, and compost manufacturing programs more sustainable.